Polymer Tacticity Control for Stereoselective Ring-Opening Polymerization of Racemic n-Propylglycolide

The synthesis of stereoregular aliphatic polyesters with superior (bio)-degradability and recyclability has been one of the promising areas in material science, which can be achieved through the stereoselective polymerization of cyclic esters. However, it remains a long-standing challenge to achieve tacticity (isotactic and heterotactic) control of aliphatic polyesters in one catalytic system through modulation of the polymerization mechanism. Here we reported a tunable and controllable method for stereoselective polymerization of racemic n-propylglycolide ( (n) Prgl) based on the analysis of the enantiomorphic site control (ESC) and chain-end control (CEC) mechanisms in the polymerization. The enantiomorphic site control and chain-end control-dominated stereoregular polymerization processes were achieved via adjustable polymerization conditions, producing isotactic poly-(( n) Prgl) with a P- m of up to 0.88 (based on ESC) and heterotactic poly-( (n) Prgl) with a P r of up to 0.94 (based on CEC). This understanding of ESC and CEC mechanisms might provide a compelling guidance to the design of stereoselective polymerization.